This invention relates to new antibiotics, namely caprazamycins A, B, C, E and F or pharmaceutically acceptable salts thereof, which have excellent antibacterial activities. This invention also relates to a process for producing a caprazamycin. Further, this invention relates to a pharmaceutical composition, particularly an antibacterial composition, comprising a caprazamycin or a salt thereof as an active ingredient. Still further, this invention relates to Streptomyces sp. MK730-62F2, as a new microorganism, having a characteristic nature that it is capable of producing a caprazamycin.
In chemotherapy of bacterial infections, particularly chemotherapy of infections of acid-fast bacteria, there have hitherto been used rifampicin, kanamycin, streptomycin, viomycin, capreomycin, cycloserine and the like, as antibacterial drug.
A serious problem for the chemotherapy of the bacterial infections is in that bacteria causative for the bacterial infections become drug-resistant. In particular, the appearance of acid-fast bacteria which are resistant to rifampicin, kanamycin, streptomycin, viomycin, capreomycin cycloserine and the like has brought about a social problem in respect of the chemotherapy of these bacterial infections. Thus, there is now a keen request for providing a novel chemotherapeutic agent which is effective against the bacterial infections as induced by the acid-fast bacteria resistant to antibacterial drug. Strongly requested also is a novel chemotherapeutic drug effective against the bacterial infections which are induced by atypical acid-fast bacteria and for which no chemotherapeutic treatment has been established yet. In order to meet these requisites, therefore, there exists a strong demand to find out or to create novel compounds which have novel chemical structure and can exhibit good properties such as excellent antibacterial activities in a different way from those of the known antibiotics as hitherto utilized. The object of this invention is therefore to provide novel antibiotics which have excellent antibacterial activities and are capable of meeting the requisites as above-mentioned.